Taurine and electrical activity of the heart

Abstract

The effects of taurine on the electrical activity of the heart were studied in isolated preparations from guinea pigs and in situ hearts of dogs that were administered toxic doses of strophantin K. In the 1st min after exposure of isolated hearts to taurine (0.05 mg/mv or more), the height of the T wave increased, the S T interval lengthened, and bradycardia ensued. At high taurine concentrations (10 mg/ml), inversion of the T wave and downward displacement of the S T segment were observed. Taurine restored abnormal electrocardiograms (ECGs) to normal, including S T segment abnormalities, T wave inversions, and disorders of conduction. On the other hand, taurine aggravated the ECG abnormalities seen in hearts perfused with K + free buffer, but sustained electrical activity if added early in the period of potassium deficiency. Taurine uptake by the isolated heart was estimated by disappearance from the medium and was found to be intensified by K + depletion. In dogs given toxic doses of strophanthin K, taurine reversed the ECG abnormalities in the initial 40 to 50 min, after which the abnormalities reappeared. If toxic effects were not present, taurine exerted an inotropic effect. These findings indicate that taurine is able to regulate the excitability of the myocardium, possibly by modifying membrane permeability to potassium. It is suggested that this effect involves penetration of taurine into the cell and its conversion to isethionic acid.